Hi Becky,
Welcome to the Disney Parks Moms Panel and thanks for sending us your question. I am so happy to hear that you are planning on attending
Mickey's Not-So-Scary Halloween Party with your family, it is my absolute favourite special event at Walt Disney World Resort! Make sure you take the time to see the Boo-to-You Halloween Parade, the Headless Horseman is a sight to be seen!
I have some good news, if you are already in Magic Kingdom Park there is no need to exit and re-enter the Theme Park when Mickey's Not-So-Scary Halloween Party begins. There will be Cast Members handing out event bracelets throughout the Theme Park, so all you will need to do is find a Cast Member who will then check you and your party in and give everyone their bracelets. From there, relax and enjoy the party! Make sure you bring a bag for Trick-or-Treating at select locations throughout Magic Kingdom Park. There will be bags available, but I like to bring my own, as the plastic handles tend to start hurting my hands by the end of the evening.
I hope you have a magical time at Walt Disney World Resort, Becky. Please let us know if you have any other questions, we are always happy to help.
Stephanie